Study On Goaf Gas Migration Laws Of Partial W-type Ventilation System In Comprehensive Mechanized Coal Mining Working Face

This paper is aimed at introducing our research results of gas migration laws in the partial W-type ventilation system.As a matter of fact, the gas from the goaf is believed discharged via the underground ventilation system.The safety and reliability of ventilation system directly determines mine safety,so it is one of the critical issues for coal mine’s safe production.However, it is beyond the current U-type ventilation, which is unable to dilute the gas content properly, particularly in the case of mine with high-gas ingredient, for example, the disallowed gas concentration in the upper corner and return airway.Based on the practice of the partial W-type ventilation of Duanwang Coal Mine as background,the gas migration laws is researched by using therotical analysis, numerical simulation and experimental in field. Under the condition of damage range of the overlying strata, space equations of porosity in the goaf porous media and calculating model of gas moving in goaf, the gas migration was researched by numerical simulation. Meanwhile, the experimental of the partial W-type ventilation to the working face090702of Duanwang Coal Mine was done in field.Research conclusion is as follows:The frictional resistance of the partial W-type ventilation is half of the U-type; In the same conditions of ventilation quantity supplied, the pressure difference in the partial W-type ventilation between the goaf and the working face should be lower than the U-type ventilation, which can reduce the air leakage in the goaf and the gas emission from the goaf; In the same conditions of model and boundary, the disallowed gas concentration in the upper corner and return airway occurred in U-type ventilation, return air roadway gas concentration is more than2.3%, while that of the partial W-type is0.4%; Therefore, with the same gas emission rate and the air supplying volume in the working face, the gas concentration in the working face with partial W-type ventilation can surely be much lower than the U-type ventilation; The partial W-type ventilation system of two intakes and one return is the best model, that of pressure difference in the partial W-type ventilation between the goaf and the working face is much lower than others, that of the distribution of air leakage is not easy to develop in the goaf, that of with lower wind velocity in working face and no eddy current in the upper corner; There is no necessary connection between the gas emission and the width of coal pillar with the partial W-type ventilation; Air distribution ratio is between1:1-3:1under the coal pillar withl5m wide; What is more, the position of the upper corner in the partial W-type ventilation is nearby intermediate return airway, while that of U-type ventilation is nearby the railway laneway.